1.4.4.1 Conversion from PCIe Write to AXI Write Transactions

A single PCIe write transaction is converted into multiple AXI write transactions at the fabric interface whenever the AXI write address space crosses the negotiated maximum payload size boundary. For example, the negotiated maximum payload size is 256 Bytes, then the address boundaries are 0x000, 0x100, 0x200, 0x300, …, 0xE00, 0xF00. In this case, a PCIe write transaction writes a TLP with payload of 24 Double-Words, that is, 24 × 4 = 96 Bytes. The write transaction targets the contiguous AXI write addresses starting from 0x0005AAF0. With a payload size of 96 Bytes, the ending write address is 0x0005AAF0 + 0x50 = 0x0005AB50, which crosses the 256 Byte boundary. The bridge breaks it into two AXI write transactions—AXI write transaction starting at 0x0005AAF0 with 16 Bytes and AXI write transaction starting at 0x0005AB00 with the remaining 80 Bytes.